diff --git a/jedi/evaluate/signature.py b/jedi/evaluate/signature.py
index 32e51caf..2871e954 100644
--- a/jedi/evaluate/signature.py
+++ b/jedi/evaluate/signature.py
@@ -1,4 +1,5 @@
 from jedi._compatibility import Parameter
+from jedi.cache import memoize_method
 
 
 class _SignatureMixin(object):
@@ -80,6 +81,7 @@ class TreeSignature(AbstractSignature):
             return ''
         return a.get_code(include_prefix=False)
 
+    @memoize_method
     def get_param_names(self, resolve_stars=False):
         params = super(TreeSignature, self).get_param_names()
         if resolve_stars:
diff --git a/jedi/plugins/stdlib.py b/jedi/plugins/stdlib.py
index f09895a2..f53e3110 100644
--- a/jedi/plugins/stdlib.py
+++ b/jedi/plugins/stdlib.py
@@ -516,7 +516,7 @@ class PartialSignature(SignatureWrapper):
         self._skipped_arg_count = skipped_arg_count
         self._skipped_arg_set = skipped_arg_set
 
-    def get_param_names(self):
+    def get_param_names(self, resolve_stars=False):
         names = self._wrapped_signature.get_param_names()[self._skipped_arg_count:]
         return [n for n in names if n.string_name not in self._skipped_arg_set]
 
@@ -598,7 +598,7 @@ class DataclassSignature(AbstractSignature):
         super(DataclassSignature, self).__init__(context)
         self._param_names = param_names
 
-    def get_param_names(self):
+    def get_param_names(self, resolve_stars=False):
         return self._param_names
 
 
diff --git a/test/test_evaluate/test_signature.py b/test/test_evaluate/test_signature.py
index 76da4fee..aa86413b 100644
--- a/test/test_evaluate/test_signature.py
+++ b/test/test_evaluate/test_signature.py
@@ -181,7 +181,7 @@ def test_nested_signatures(Script, environment, combination, expected, skip_pre_
     code += 'z = ' + combination + '\nz('
     sig, = Script(code).call_signatures()
     computed = sig._signature.to_string()
-    if not re.match('\w+\(', expected):
+    if not re.match(r'\w+\(', expected):
         expected = '<lambda>(' + expected + ')'
     assert expected == computed